Inaugural speech prof.dr.ing. Z. Li (CiTG): railways

Contact modelling and contactless monitoring

A railway track system degenerates under dynamic loading. This loading arises from the interaction between trains and tracks through wheel-rail contact. It excites dynamic responses in the system, in its components and at the interfaces, causing changes in their health conditions by wear, deformation and fatigue.

By optimal design, maintenance and renewal of the system, components and interfaces, the loading-response relationships can be affected so as to greatly reduce the degradation rates and consequently the life cycle costs. Such maintenance and renewal can be achieved by monitoring the dynamic loading-condition-response relationships so that they can be performed predictively and preventively.

The challenges are to establish the loading-condition-response relationships and to develop methods that can detect small changes in the relationships and can pin-point what problem is happening at which place and how severe it is, before the assets degenerate exponentially.

I will tackle the following 3 aspects to meet these challenges:

Solving the contact mechanics problems in the train-track system to determine the dynamic loading-response relationships for the components and the interfaces. The key problem to address is dynamic friction in Coulomb friction law.

Establishing the loading-degradation-microstructure relationships of the components’ materials. The focus will be on steels. These will establish loading-condition-response relationships that can be used for the optimal design and will be sued for

Developing an all-round monitoring method for predictive and preventive maintenance and renewal. The key problem to address is precise detection of anomalies with contactless laser Doppler vibrometer that continuously scans tracks from trains.

The 3 aspects are unified by the underlying dynamics of the system with a consistent multi-scale modelling and multi-resolution measurement approach.